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br-parser-tools/collects/parser-tools/private-lex/actions.rkt

17 lines
577 B
Racket

#lang scheme/base
(provide (all-defined-out))
(require syntax/stx)
;; get-special-action: (syntax-object list) syntax-object syntax-object -> syntax-object
;; Returns the first action from a rule of the form ((which-special) action)
(define (get-special-action rules which-special none)
(cond
((null? rules) none)
(else
(syntax-case (car rules) ()
(((special) act)
(and (identifier? #'special) (module-or-top-identifier=? (syntax special) which-special))
(syntax act))
(_ (get-special-action (cdr rules) which-special none))))))